Text-to-speech (TTS) synthesis systems offer natural-sounding and fully adjustable voices for desktop, telephone, Internet, and other various applications (e.g., information inquiry, reservation and ordering, email reading). As the use of speech synthesis systems increased, the expectation of speech synthesis systems to generate a realistic, human-like sound capable of expressing emotions also increased. Singing voices that provide flexible pitch control may be used to provide an expressive or emotional aspect in a synthesized voice.